


Katydid

by songlin



Category: Sherlock (TV)
Genre: Alternate Universe - Vampire, Anal Sex, Blood, Blood Drinking, Blood Kink, M/M, Mating Cycles/In Heat, Mildly Dubious Consent, Vampire Sex, Vampire Sherlock, Vampires
Language: English
Status: Completed
Published: 2015-01-27
Updated: 2015-01-27
Packaged: 2018-03-09 06:56:02
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 12,083
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3240461
Author URL: https://archiveofourown.org/users/songlin/pseuds/songlin
Summary: <blockquote class="userstuff">
              <p>The smell of John's blood is thick in Sherlock's nose. He can hear John's heart thumping through his ribcage as clearly as if his ear were pressed against John's chest. Sherlock's mouth runs dry. He is suddenly very, very hungry.</p><p>"Like it or not, Sherlock, matters will escalate. You are tempting biology."</p>
            </blockquote>





	Katydid

**Author's Note:**

  * For [LuxObscura](https://archiveofourown.org/users/LuxObscura/gifts).



> This fic is a gift for LuxObscura, who requested it about A MILLION YEARS AGO. I promised roughly 2,000 words. This is...six times that.
> 
> This is my attempt at something that is both vampire-y and omegaversy. The consent is "mildly dubious" in that both of them want it and weren't doing it, but they ended up forced in by biology. That is the single greatest thing omegaverse allows us to do, in my opinion.
> 
> This is quite un-beta-ed, so if there's some illegible/incomprehensible bits, please let me know! As ever, I live for comments. Please, criticize me. My drive to improve is motivated entirely by my sense of inferiority. But no, really, comments, criticism, anything, lob them at me. My skin is thick. Like, if Vamplock came after this little grey duck, he'd have a time of it.
> 
>  
> 
> [Now with art by the fabulous Archia!](http://archiaart.tumblr.com/post/130492965361/songlinwrites-sherlock-just-whines-leans)

Sherlock lies supine on their leather sofa with his hands tucked under his chin. He's just drunk half a pint of donated blood, which has taken the edge off his thirst. It hasn't fully sated him. Bagged blood never does, and it leaves a nasty chemical aftertaste. But it's better than nothing, especially when living in close proximity to temptation.

At present, temptation is making his own bachelor's supper in micro while idly flipping through the paper. It occurs to Sherlock that he has not spoken to John yet today, having been asleep when John left and not yet communicative when he arrived home. He files this note in a place of relative importance: accessible, but not urgent.

Sherlock scowls. His meager dinner was most insufficient, just short of completely futile. Already he can feel the twinges of thirst in the back of his throat. But he won't give in just yet. This is an exercise in control.

Sherlock inhales through his nose and parses through the different scents. He sorts through and discards the smell of microwave soup and the background aroma of the flat until he catches hold of the olfactory thread he's looking for.

_Lingering sweat—went for a jog earlier, plans to shower after dinner. Talcum powder from the gloves at the clinic. Spilt tea on his sleeve—cheap, bagged English breakfast with milk, no sugar—woke late, left in a rush, drank tea en route._ Beneath that, there is the "John" smell, something like gun oil and rising bread and sand and copper. Sherlock catches it in flashes, and just that is elating. He tries to sift that scent from the sediment. He is certain that if he can, he will nearly be able to taste it in the back of his throat. That would be...good. It might be almost as good as tasting John in life.

But the background noise is too strong, and Sherlock gives it up as a bad job.

"Sherlock?"

He opens his eyes.

John is standing between the kitchen and the living room, soup in hand, looking ever so sweetly bemused.

"Sorry," he says. "You just looked rather…dead."

Sherlock smirks.

John smiles and ducks his head. "You know what I mean. Hungry?"

"Gasping."

It's not until he's half-drained the bag of blood John heats for him that he remembers he was to be denying himself.

Perhaps tomorrow. Tonight, he is energized, recharged, and his phone is ringing. He picks it up and grins.

"Case."

There is a woman in the bins behind 12 Downing Street.

"Worked for the Prime Minister's press office," says Lestrade. "So, motive's probably—"

"Don't!" Sherlock snaps. "You're of no use at all if you've biased yourself prematurely. Or don't we construct cases based on _evidence_ anymore?"

John and Lestrade exchange a Look. John bends down beside Sherlock as Sherlock exposes the woman's arm to reveal a number of sharp crimson pockmarks on her light brown skin. Lestrade hisses a breath in through his teeth.

"Drugs?" he says.

Sherlock shakes his head. "Masquerading as."

John's eyebrows lift. "Track marks don't come in pairs."

"And?"

John looks again, thinks—

"They're all the same age."

Sherlock nods and drops the woman's arm.

"Fantastic. Bloody wonderful." Lestrade presses his knuckles to the bridge of his nose. "Exactly what I wanted to do today."

"Oh, _don't_ ," Sherlock says, wrinkling his nose. "We don't need him."

Lestrade snorts. "Oh, you're going to cover for me when my boss comes asking what happened with that body at Downing Street and I have to tell him it was ruled accidental? Or no, you'd rather I tell him she—" He checks behind him and lowers his voice. "—tell him she was _eaten alive by_ _fucking_ _vampires!"_

_"Shh,"_ Sherlock hisses. "If you don't consider yourself capable of lying to a superior—"

"Oh, 'consider myself'!"

"—or solve a case without his assistance, then feel free to give up and hand it over."

John rises to his feet and puts a hand on Lestrade's chest. "Greg, come on."

Greg scowls and turns aside.

"And _you_." John rounds on Sherlock. "Have you got something?"

Sherlock grins.

Naturally, he does have something. The disguising of bite marks as needle marks is an innovation only found in a few circles, which narrows the pool significantly. Additionally, few mature vampires are careless enough to drain someone dry—especially someone of importance—and then leave the body where it would be found. It can only be a newborn without a sire. If they had left, they would be trying to lay low. Sherlock knows that game firsthand. This is not "lying low." This is a cry for attention. For certain, this lost lamb was abandoned. Sherlock will find the progeny first, then the parent. The latter is trying not to be found. The former doesn't know how.

Sherlock explains all this to John on the way back. John takes it in with the faint smile he wears before he tells Sherlock he's brilliant, and then he does just that. It's wonderful.

Of course, Sherlock missed something.

They detect the change as soon as they open the door to the flat. For Sherlock, it is the stench of blood, fresh and dank with fear. For John, it is…whatever it is that he senses when a situation is about to go south. In any case, he knows too, because his gun is out and he's drawn into himself very deeply, as he does just before he fires.

Sherlock goes up first. It will take anyone significantly longer to kill him. As it turns out, it's unnecessary.

A woman is sitting on their floor, her whole front covered in blood. She holds her hands out to them in a gesture of supplication.

"Help me," she sobs. "He's out of my control."

———

Sherlock loves this case. He can't remember ever being so thrilled to be wrong in his life. God, he _loves_ this case.

Dolores, it transpires, was a newborn, and had been abandoned by her sire barely a month after her Change. While feeling her way alone, she took a young male lover, Jack Fergus. After revealing her nature to him, he became quite enamored of the idea of immortality. Dolores was less enthusiastic. To her, immortality had been a sentence. To Jack, it was an opportunity. Eventually, Jack grew tired of being turned down, and started plotting to attract the attention of other, more amenable vampires.

"Jack knew her," Dolores says quietly. She squirms, uncomfortable in her bloody dress. Sherlock was unwilling to give her a change of clothes or a shower until she has finished her story and he judges its truth. She is a crime scene until proven otherwise. "He knew that I'd bitten people like that sometimes, when I was—before. Never to death, mind. Just enough. And he fed me some of her blood. He knew that others would come if there was a…spectacle." She shrugs and looks down at the floor. "So he made one."

Sherlock rubs his finger over his lips.

He is repulsed. How _dare_ he. How dare that monster worm his way into this woman's trust, find her soft underbelly, and tear into her. How dare he expose them all to danger for his own profit. This man is disastrously reckless.

And yet, Sherlock is also electrified. A human abusing a vampire—novel! As much as he wants to liberate this man's limbs from his body, he wants to kiss this woman and twirl her around for this utter _gift_ of a case.

Sherlock looks to John. His forehead is so wonderfully rumpled just now. He looks that way when he's _feeling_ for someone. He feels for Dolores now. And yet, when John looks at Sherlock, raises his eyebrows, and flicks his eyes back to Dolores, it's not entirely sympathy. There's…thrill.

The corner of Sherlock's mouth curls up as if to say, "You too?" Something sparks in John's eyes before they slide sideways back to Dolores.

"Thank you," Sherlock says with relish.

John shoots him a quick look, a silent "watch it." Sherlock pretends not to notice.

"Where do you live?" he asks Dolores.

"Croydon. Few blocks from Clissold Park. I'd take you, but I…" Dolores looks down at her soiled clothes.

"Go and see Mrs. Hudson. You'll find her quite prepared to help," Sherlock says. He is already getting up and reaching for his coat.

John frowns. "What, is she not coming?"

"Smells too strongly of trap," says Sherlock. "Come on, we're wasting moonlight."

———

Dolores's first-floor room looks more like a student's bedsit than a vampire lair. The bed is a spring mattress on the floor covered with an old, worn duvet. The attached kitchen is practically empty. The furnishings throughout the room are sparse. There is a battered sofa, likely rescued from a rubbish tip, sitting in front of a television that is probably older than the body they saw earlier that night. The rest of Dolores's belongings seem to consist of a rickety desk and chair holding a gray laptop, a few shabby bookshelves, and a couple cardboard boxes filled with clothes.

Sherlock circles the room. He passes over the kitchen, only glances over the desk and shelves, kneels by the bed, and sniffs. He sniffs again, wrinkles his nose, and grins.

John smiles, bites his lip, and shakes his head. "Go on."

Sherlock frowns. "What?"

John is very slightly smiling and shaking his head. "Go on, do it."

"Do what?"

"Deduce." John gestures at the apartment and looks back at Sherlock with a kind of silly fondness. It makes Sherlock's chest hurt.

He clears his throat. "What's wrong with this bed?"

John comes over and leans over Sherlock's shoulder. "Um, I dunno."

"Come on, John, _look."_

John scowls and peers closer. "Looks fine to me. Quite nice linens."

Sherlock grins. "Exactly."

"What? The sheets are nice?"

"The sheets are _expensive,"_ Sherlock corrects. "They're new. Specially purchased. I guarantee you that when this is sent to the lab, it'll turn up soaked in garlic. Pickled garlic, specifically, so as to neutralize the smell."

Realization dawns. "We've got evidence he was trying to hurt her—"

"Exactly."

"—which validates her story," John finishes. "Alright, then, so we can prove to Mycroft and his people that Dolores is innocent. Will that be enough for them to take down Fergus?"

Sherlock grimaces. "I don't know."

John shrugs. "I'll call up Lestrade. He's got the stuff to gather the—"

The shot is the first warning Sherlock has that they are not alone.

In the fractions of fractions of seconds between the shot and its target, he grabs John's arm and pulls him down. John cries out. Sherlock smells blood. His head whips toward the door, snarling, in time to see Jack Fergus fleeing into the street.

John has dropped to one knee and has his hand to his arm. When he brings it away, there is a smear of red on his palm.

"Shit," John hisses.

Sherlock's stomach goes cold even as his thirst flares hot. He jerks John's hand away to get a look at the wound.

"Shallow through-and-through," John says. "Go, I'll catch up."

Sherlock does not wait to think. He gets to his feet immediately and races after Fergus.

This isn't just a case now. This is a _hunt_ , and his blood is up. He reaches out with all his senses, plucking out sounds and smells and evidence, the wheat from the chaff.

_street on the right/round the corner/down the left stairs/alley behind the grocery—there!_

Sherlock catches Fergus by the back of the neck, hauls him backwards, and shoves him against the wall. Sherlock pins him there with his hand around Fergus's neck. Fergus's head bangs into the brick with a satisfying dull thump. He lets out a short grunt and blinks slowly.

Sherlock bares his teeth like a feral beast. Fergus laughs.

"Yeah," he breathes, "do it, please. I want your gift. I'll do anything. Please."

Sherlock slams him into the wall again. This time, something shakes loose in his brain. Fergus seems to comprehend that something here is not as it should be. His prey instincts are starting to come to life, only just too late to save him.

"I should leave you to die," Sherlock hisses.

Fergus's mouth goes wide. He jerks and pulls uselessly at Sherlock's hands.

Sherlock can smell his acrid fear rising over the disinfectant and the blood— _so_ much blood. Fergus hasn't changed his shirt since setting up the gory scene from earlier, only put a coat over it, and he reeks of the dead girl's last heartbeats. It unfurls something basic and dark in the back of Sherlock's head. It creeps forward and blankets him with cold. His shaking and snarling still into something calmer and far, far deadlier.

Sherlock smiles. This is going to taste positively _sinful_.

"Sherlock."

He is pulled back. The frigid calm recedes, and he is enraged again, furious and bestial.

John looks unfazed. His gun is out and aimed at the awful man, and his arm is rock-steady.

"Put him down," John says.

"He'd _deserve_ it." Sherlock's voice comes out layered with intent, both cavernously deep and piercing at once. Fergus, still pinned to the wall, cries out, jerks back, and bangs his head into the brick again.

John does not quite flinch. The corners of his mouth pull ever so slightly tighter, though, the only sign of discomfort he allows. "He would. But put him down."

Sherlock's face twists. "Why?"

"You haven't got the time to hide the body."

Sherlock listens. John is right. The police will be on their way. John will have called them. Sherlock cannot drink him down and get away in the time they have.

With a final snarl, Sherlock lets Fergus drop and twists away. He hears, rather than sees, the scum slump against the wall.

"Thank you," he gasps to John, "oh, God, thank you."

"You're welcome," John says, and cracks Fergus over the head with the butt of his gun. He crumples to the ground.

Sherlock turns round and stares, dumbfounded.

John shrugs. "Couldn't let him run away, now, could I?"

Sherlock cocks his head and smirks. The dark thing in the back of Sherlock's head purrs with delight.

"Better get a move on," John says. His eyes are blazing and he's postured strongly and confidently. "People might think we're up to something."

_I could have you here until you cried out for the end,_ Sherlock thinks. His eyes drift downwards. John is half-hard, the outline of his cock clear and defined in his corduroy trousers. The smell of John's blood is thick in Sherlock's nose. He can hear John's heart thumping through his ribcage as clearly as if his ear were pressed against John's chest. Sherlock's mouth runs dry. He is suddenly very, _very_ hungry. How long has it been? Has he drunk anything since the case began?

John sees him seeing. He goes still, and Sherlock wonders if he realizes what he's doing with his body. Is he conscious of the rigidity of his posture, the subtle shift in weight that brings his center of balance in? Does he know he has opened his hands and turned them out just so, ready to grab and hit and fight?

"Sherlock," John says, somewhere between a question and a warning.

"John," Sherlock simply _growls_.

It's only a matter of time before one of them moves. Sherlock can hear John's pulse racing in anticipation.

But then, an earsplitting noise makes itself known on the outskirts of his senses. He grimaces. Three squad cars pull up in a scream of sirens and flashing lights. John and Sherlock break eye contact, Sherlock pulls back into character, and the moment passes.

———

John tries to think of Sherlock's…state…as a condition, like gluten intolerance or diabetes. Sherlock has to stay fed, or there are consequences.

Only, when Sherlock doesn't follow through on his dietary needs, he doesn't go into anaphylactic shock or a diabetic coma. Instead, he goes hollow-cheeked and predatory, staring down people like a wolf on the hunt. 

Those are the moments John is almost afraid of him. In a way, he _is_ afraid. But it's not quite the right fear, the sort he knows he _should_ feel. It's not the ice-cold fear of a gun to his head that freezes him solid. No, it's the sort that makes his cheeks flush and his limbs come alive, the kind that cures his psychosomatic limp and keeps his hand steady. Sherlock isn't a threat that John needs to avoid. He's the kind of threat that John needs like water.

But _God_ , he's dangerous. John tries to temper the temptation with sense and perform proper risk assessments before he lets Sherlock do something mad. It's worked so far. John isn't sure how feasible a solution it is in the long-term. He'll deal with that as it comes.

For now, it's a matter of telling himself not to walk over to Sherlock, kneel, and offer his throat. John is a medical man after all, and it's difficult not to provide a patient with the simplest solution.

But he has to draw the line somewhere.

———

"You can't go on like this," Mycroft says.

Sherlock, in his blue dressing gown and deepest levels of ennui, rolls over and faces the back of the sofa with a melodramatic sigh. "Don't be tiresome."

"I am not _nagging_ , Sherlock, I am trying to help you."

Sherlock sneers.

"Like it or not, Sherlock, matters will escalate. You are tempting biology."

Sherlock has stopped listening entirely. Mycroft is still talking, something about aggressive mimicry and adaptive manipulation and complex signal-response systems and obligate symbiosis, but Sherlock doesn't want to take in anything he'll have to delete later. Nothing coming from Mycroft right now could _possibly_ be of _any_ use to him, _ever_. So he lies still on the couch, doesn't even pretend to breathe, and waits until his brother finally gives up and shuts the door behind him with only a tad more force than strictly necessary.

———

Sometimes, John suspects that his motives for wanting to keep Sherlock fed are not entirely altruistic.

Because in John's dreams, a starving Sherlock does not slink off to parts unknown to drink via methods unknown. In his dreams, John lies back while Sherlock looms over him and tips John's head back, baring his neck.

Sherlock says something like, "Come, now. What are you so afraid of?"

And John shivers. "That you’ll lose control."

Sherlock will chuckle. His laughter is a dark thing, with teeth and claws. "Is that all?"

"No." John squeezes his eyes shut and swallows. "I’m afraid I want you to."

Sherlock sighs like he’s been given a gift and _bites_.

Every time, that is the moment that John wakes with a muffled cry shortly before cursing, rolling over, and taking his throbbing prick in hand.

———

Sometimes, the donations aren't enough.

Sometimes, the thirst is too much for him to bear, burning in his throat and mind and driving him to distraction. It's not like hunger that way. You don't feel hunger like a fever. When it's too much to bear, he gives in, gets changed, and goes on the hunt.

In his youth, he had at his disposal the opium dens and brothels. The girls were always glad to earn full wages for half the work—it was just a bit of necking, after all. And frankly, Sherlock posed less of a risk to their health than their usual clientele did. After, he paid well.

The opium addicts were different. They would not be bought. They had to be seduced, lured into Sherlock's influence. Drinking from them made Sherlock unpleasantly lightheaded. As the authorities cut down on opiate abuse, Sherlock's hunting grounds gradually shifted to their current form: crack houses. Cocaine was vastly preferable to opium. It made the world brighter, not blurrier.

Sherlock slouches into a rundown house with his hood up and his head down. A boy at the door nods in recognition. Sherlock shuffles up the stairs.

He enters a room filled with makeshift cots and sleeping bags, scattered with the detritus of hundreds of addicts. A girl by the door scrambles over and grabs at his ankle.

"Hey," she whispers urgently. "Have you got anythin'?"

Sherlock nods. It isn't a complete lie.

The girl's eyes go lax with anticipatory pleasure. "How much?"

Sherlock names a price. It doesn't matter. She doesn't have enough for anybody to give her anything.

Her face tightens. "Never mind."

Sherlock shrugs and turns away.

_Three…two…one…_

"Wait! Wait."

Sherlock stops.

The girl looks down. "Could I…arrange somethin'?" She looks up through her eyelashes, a child playing the coquette.

Sherlock's stomach turns, but he nods.

He always does it after he kisses them, once they're well under. It isn't that they don't feel their head tip back and the punch of teeth through flesh. It's more that it's transmuted, filtered through perception and Sherlock's influence. Sometimes they are silent. This one is not. When Sherlock bites down, she lets out a little noise like a startled child. Sherlock does not listen. He drinks.

When the desperation subsides, so does he. He lays the girl down on the dingy sleeping bag. She has fallen asleep.

In the morning, she will remember little. It will not be a new experience. Sherlock, though, remembers every one.

———

If not for the poor aim of one Douglas McMurdo, they may have carried on in that manner forever.

The short of it is that Sherlock gets shot. It would've killed John, but Sherlock got in the way just in time. McMurdo locked them in his basement while he worked out a disposal plan. Sherlock, of course, fails to bleed to death.

But then he doesn't start healing either.

"What's wrong?" John whispers. "Shouldn't you be…you know, bashing his face in by now?"

Sherlock is on the floor where he had fallen (with possibly unnecessary drama) after he was shot. He has pulled himself to a sitting position with his legs out in front of him. There is a dark but bloodless hole through his shirtfront. Even in the absence of blood, he still looks…well, _shot_. Like his strings have been cut.

"I'm experiencing a, ah," Sherlock winces, "setback."

John's mouth twitches. "A setback?"

Sherlock gingerly prods the hole and hisses. "Healing requires a certain amount of—"

"Jesus fucking _Christ_ , Sherlock, you haven't eaten in _ages_ , haven't you?"

Sherlock frowned. "Ah! Yes, I've got it. Sorry. Working through—double negative. Yes. You're—correct, that is."

John throws his fists up into the air. "God _damn_ it!"

Sherlock grimaces. "Sorry."

John is going to _murder_ him. At the very least, he's eating nothing but Italian for a month. The whole flat—no, the whole _street_ is going to reek of garlic.

Right, then: later, there will be repercussions. Now, though, they need to get out.

There's no lock to pick on their side. It's padlocked on the other end. Sherlock could ram them out, but he's about as useful as tits on a bull at the moment. Even if they could get out, there's McMurdo to deal with. John is unarmed and unaided. Not good chances.

John stops and sighs. He looks at Sherlock, then to the door, then back to Sherlock. His mouth sets into a firm line.

"Well, then," he says, rolling up his sleeve.

Sherlock's eyes go wide. He shakes his head. _"No."_

"Well, it's not like we've a lot of bloody options!" John becomes aware that he is shouting. He lowers his voice. "Even if you drained me half dead, you'd be able to get us out and me to a hospital. You could even blame McMurdo." He kneels at Sherlock's side and offers his arm with a brusqueness he doesn't feel.

Sherlock's nostrils flare. "John, you don't know what you're—"

"Ah, I do, actually."

Sherlock shoots him a suspicious glare. He has turned a grey color John is familiar with only in oldish corpses. When he shuts his eyes for a slow blink, he looks the part of one. John's will cements.

"Here, I'll make it easier on you," he says.

John takes his pocketknife from his back pocket, flips it open, and quickly nicks his wrist. Blood beads on his skin.

Sherlock's eyes go dark. _"John,"_ he breathes.

John's stomach is churning. There's a tight feeling in his chest. He focuses his attention on breathing with the utmost care.

"Do it," he says.

Sherlock seizes John's arm and presses the cut to his mouth.

His fangs sink in on both sides of John's small incision. John hisses, but it doesn't hurt as much as he'd thought. Less wild animal attack, more of a blood donation.

Well. Maybe not _just_ a blood donation.

As Sherlock drinks his blood in alternating long pulls and measured sips, something and John rises and falls with it. For all Sherlock's strength and the danger he poses, John feels oddly protective. How can he have missed how much this creature relies on him?

John's balance is unsteady. He puts his free hand on the wall and leans his weight onto it. Sherlock lets out a long, shaky, nasal sigh that raises the hairs on John's arm. John's lips part. His eyelids lower.

Sherlock pauses in his rhythm to lap up a trail that has dripped down towards John's hand. John lets out a small, surprised noise. Sherlock responds with something deep and primal and grateful, and John shivers.

John lets his eyes drift shut and relaxes into the ebb and flow of the drinking. He loses the passing of time and listens to his heartbeat.

_thump-thump, thump-thump, thump-thump_

Eventually, Sherlock unclamps his jaw and slides his teeth out. John gasps, just a little, more in surprise than pain. Sherlock licks at the two neat holes in John's wrist. They seal over almost immediately into two neat, clean, dark spots. John smiles. He suspects he looks rather drunk.

"Better?" he asks.

Sherlock nods. He certainly seems better. John looks closer and notices Sherlock's pupils are dilated. Have they always done that when he feeds? John can't remember. "Much," says Sherlock. "How do you feel?"

John giggles. "Er—leaky?"

Sherlock's face flattens into a look of alarm. _"John."_

John bites his lip. "Yeah. Sorry. I'm a bit—giddy, but that might just be the, um—stress. That."

"The bite triggers a massive endorphin release," says Sherlock. He is checking John's pulse at his neck.

"Lot like being shot, then," says John with a wink.

Sherlock is caught off-guard for a second. But then John grins, and Sherlock grins, and he's pulling John to his feet and looking luminous.

"Now," he says, "shall we catch this murderer?"

———

John is still humming with energy when they get back at three in the morning. He eats half a pizza, and goes to bed. By seven, he's awake, alert, and itching to get something done, so he decides it's as good a time as any to do a bit of tidying-up. When he's finished scrubbing the bathroom down, he starts in on the kitchen.

Sherlock makes his appearance at half-past nine. John looks up from where he's scouring grout out of the tiles, and his feet nearly go out from under him.

He is overcome by a rush of…affection. There's no other word for it. He looks up at Sherlock, still in his pyjamas and dressing gown, hair rumpled and skin still glowing with life from his feeding last night, and is devastated by a wave of feeling.

Sherlock yawns. His two long, sharp fangs glint in the darkness of his mouth. The bite at John's wrist tingles.

John realizes he is staring. "Um," he says. He clears his throat. "Morning."

Sherlock looks a bit dazed, but that could just be because he's just gotten up. Vampires are not renowned "morning people."

"Cleaned the bathroom," John says.

Sherlock nods. "Oh. Yeah. Good."

They are still staring at each other. John's stomach is churning and his face feels very warm. He can't shake the urge to cross the room and…do something. Just be _closer_.

To break it, he turns away. "Might do Mrs. Hudson's later today."

Sherlock clears his throat. "Yes."

John can't quite shake the sense of disappointment.

———

Sherlock is thirsty.

No, Sherlock is _parched_. He's approaching malnourishment. He's drunk some, but nothing satisfies. The thought of hunting turns his stomach, and yet the thirst burns in him in a way he can't remember it ever feeling. He thinks back to the grey-tinted years before he was bitten. Was there anything in mortal life that felt like this? He doesn't think so, but he can't be sure.

There is always a tinge of lust to the thirst, but it's different now. Lazier. Sherlock lets his hand rest on his ribcage. Desire flares in his chest, hot and unhappy. He grimaces.

Sleep. He needs to sleep. It will be quieter there. He closes his eyes.

It is not quieter. He lies awake, staring at his ceiling or curled into himself while a strange, sick feeling roils in his guts. His chest hurts. The thirst is intense enough to burn sometimes, and nothing he drinks will slake it for long.

_This cannot continue,_ he thinks, as he finally slips into a wretched, restless unconsciousness. _Something must break._

———

A week after the incident in the basement, Sherlock looks up to call John over at the precise moment he reaches up into a high cabinet. His sleeve pulls back to reveal the two small, pink circles on his wrist, and Sherlock briefly loses the capacity to speak.

Sherlock can remember, in perfect clarity, the pang of teeth through skin and the warm, sweet rush that swept through him. He could be there right now. It terrifies him for the moment it lasts.

After it ends, Sherlock is left trying to shake off the craving that lingers in his bones.

———

Two weeks after, Sherlock goes out. John disregards this whenever it happens, because he knows Sherlock is almost certainly doing nothing he wants to think about.

Nevertheless, he's jittery and on-edge for the full two hours he's gone.

———

A month after, when the scars on John's wrist are barely noticeable, he slams a cupboard door shut and whirls on Sherlock with narrowed, suspicious eyes.

"Have you drugged me?" he demands.

Sherlock can't even muster the energy to look offended. He simply lolls his head back and forth once in the laziest head-shake _"no"_ that John has ever seen.

John frowns. Even for his standard ennui, Sherlock seems...off. John can't pinpoint quite what it is, but there's something about the way he moves and looks and seems that isn't quite meshing. He quashes the urge to feel for a fever.

"Hey, are you...okay?" The question feels strange. Sherlock did somehow survive a century without John to babysit him, after all, and it's not as if John is any kind of expert on vampire health.

Sherlock flares into life, rolls over, pulls his dressing gown over himself, and tucks his knees up to his chest. "Fine," he spits.

John sets his mug down and stands with his hands on his hips. "Oh, yeah. It's obviously fine. Why would I ever think it's not fine?"

It hits him all at once: the paler skin, the lethargy, the moods. He strides to the fridge and wrenches it open. There are no telltale bags of blood laid out on the shelves. John breathes deeply and tries to maintain his blood pressure.

"Sherlock."

Sherlock does not respond.

"Have you had anything since you finished off that last round of O positive?"

"Yes."

John goes to the sofa and nudges Sherlock's shoulder with his knee.

"Turn over and say it again."

Sherlock doesn't move. John pinches the bridge of his nose.

_"Christ,_ Sherlock!"

"You wouldn't understand," Sherlock mutters into the sofa cushions.

"I understand you'll go off the bloody deep end if you don't drink soon."

"I can't, it's all _horrid."_

"You can or I'll call your brother."

Sherlock turns over for that. His pale face has pinched into a cross expression that would be hilarious under other circumstances. "You wouldn't."

John snorts.

Sherlock grits his teeth. "Fine. I'll call Molly."

_"I'll_ call Molly."

John calls Molly. She stops by with three pints of O positive and a coffee. John takes his coffee over to his chair and supervises Sherlock fussing over his blood.

He tries drinking it cold and straight from the bag, but doesn't get more than a sip before pulling off in distaste. Next, he fetches a mug from the sink, squeezes the bag into the mug like a bottle of ketchup, and pops it in micro for a minute. He is able to finish maybe half a pint that way before he pushes it away, flops back onto the couch, and throws one dramatic arm over his forehead.

John frowns. At this point, Sherlock is usually hungry enough to lose his champagne tastes. John's never seen him fail to down at least two pints of properly heated hospital blood. Is he sick? Can vampires get sick? How would John know? It's not as if he can check for a temperature.

In any case, there's nothing else he can do tonight. He will worry about it in the morning. In the meantime, he has to sleep. That must be why he feels so…restless. A good night's rest will put him to rights.

———

Sherlock hurts.

It's a strange, nonspecific hurt, centered in the core of his body but not isolated there. His stomach cramps. He curls around his elbows and whimpers. This isn't the thirst. It _isn't_. There's tinges of it around the edges, but something else too, something liquid and heady that pools between his legs. His senses are on edge. _Everything_ is on edge.

Sherlock grits his teeth. Surely someone can stop this. At the very least, they must be able to make it better. John should know. John is wonderful at better. He is a doctor, after all.

Sherlock stumbles to his feet. He sways, bumps into the doorknob, and catches himself. John's room is up the stairs. He takes the steps one at a time, dragging his toes over the carpet on every one. But for all his current clumsiness, he is still superhuman. He can open the door without waking John.

The sight of his friend settles something in him. The smell of him permeates Sherlock's senses, curls up in his stomach, and soothes the ache.

John rolls over onto his back with a little sigh. He's wearing a vest, pyjama pants, and nothing else. His arm is thrown up by his face, the one with the two scars on the inside of his wrist like tiny white pinpricks.

Sherlock feels substantially less eased.

He lunges forward. Perhaps he falls. In any case, he's on the bed, looming over John but not quite touching. Sherlock breathes in. God, the smell of him is luscious, succulent, irresistible—

— _wrong_.

Sherlock hurls himself away. This is—false. Incorrect. Unforgivable.

Stomach chilled, he turns, flees to his room, and locks the door behind him.

———

John dreams of Sherlock again. It's unclear, muddy dreaming, the sort that doesn't quite stick in memory outside of flashes of sense-memory. Laughter like a toothed, clawed thing, pain that makes him moan with he doesn't quite know what, a feeling like pouring out of himself and then flowing back in, cleansed.

John wakes up hot and harder than he's ever been. He reaches into his pants to adjust himself, but the touch of his hand feels dry and unpleasant and wrong.

A sort of logic starts to creep back in. This feels…abnormal. Supernaturally abnormal. A hand on his cock should feel adequate, if not ideal. As he usually does when something strange happens to him, he suspects Sherlock.

Thinking of Sherlock doesn't feel wrong at all. In fact, it's more satisfying than his hand had been. John remembers how Sherlock was acting last night—the not eating, the vague malaise. He is swamped with a sudden surge of guilt, which is—also strange. It's not his fault. He didn't poison the ridiculous man. Why should he feel responsible?

Well. More responsible than usual.

Whatever the cause, he does. So John shakes his head, which almost clears it, rolls out of bed, and pads down the stairs towards Sherlock's bedroom. Sherlock's door is shut. John pushes it open and goes very, very still.

Sherlock is naked and spread out on the bed, all cream-white skin and angles like a Corinthian column. His legs are drawn up so he can sink two fingers into his arse. His other hand is between his teeth as his fangs work uselessly at his skin.

John is frozen in the doorway. He's very aware of his blood rushing to new and interesting places. He feels sick. He might _be_ sick. But the moment passes, and leaves him feeling dizzy and slow.

Sherlock grunts in frustration at his inability to bite into his hand. He tries to scratch one fang in sideways.

"Don't," John says, still thick-headed and stupid.

Sherlock covers his hand with his mouth and whimpers. John's prick throbs.

"You'll hurt yourself."

Sherlock shakes his head. He slides the hand from his mouth and down his neck, over his chest and the planes of his stomach. "Can't."

John gets in a deep breath and regrets it immediately. Too late, he recognizes the source of the unplaceable moods and extra-weird dreams and raging arousal. He staggers forward and falls to his knees next to the bed.

It's like he's been huffing a low dose of laughing gas and someone's just doubled the concentration. At the same time, it doesn't feel like any drug he's ever heard of. It's really just a smell when it comes down to it. But while the smell of food triggers hunger and the smell of blood triggers alertness, this smell triggers…want. Specifically, it triggers want of Sherlock.

"What's happening to me?" John chokes out. "What are you doing to me?"

Sherlock settles back with a full-body writhe. "It's—ah. A sort of—heat."

John squeezes his eyes shut and tries to tamp down the urge to rip his clothes off, pull Sherlock into his lap, and let him drain John dry. "That's…new."

Sherlock is squirming. "Was— _mm_. Kept at bay. Lack of— _ah_ —options."

John laughs. It's not a happy laugh. "So," he says, "you're saying you're so desperate to eat me that your entire body is trying to trick me into it."

"Something like—" Sherlock makes an embarrassed noise. "Yes, eat you. And..." His voice drops into a near-subsonic register. "...other things."

John shudders. "Oh, God."

Sherlock thrashes on the bed, agitated and miserable. "John," he whines. "John, it hurts."

It's not that Sherlock looks tempting as a marzipan candy, or that he's so starved that he's white as porcelain. Or, more accurately, it's that he's both of those things, but it's also because he is John's friend, and John wants to give him what he needs.

"Yeah," John says. He's stripping off his shirt and trousers before he fully comprehends what he's doing. Sherlock watches with lustful, heavy-lidded eyes.

When John shucks his briefs down his legs and steps out of them, Sherlock lets out a purr of satisfaction that makes John's spine tingle. "Me, John. Have me."

"Absolutely," John says.

And then, Sherlock's demeanor shifts.

He seizes John, pulls him down, straddles his thighs, and pins him by the shoulders. John is too hazy-headed to react until he's totally restrained. Sherlock is not heavy, but he is very, very strong. John realizes how lucky he is that Sherlock would not take John's blood without consent. He doesn't think he could stop it.

Sherlock drags John's left hand down between his legs, behind cock and balls, trailing over his perineum and further back. He croons as John's gentle fingers circle and then slip in.

John's eyes nearly roll back into his skull. Sherlock is wetter than any girl he's ever had, and getting wetter. As he cautiously curls his fingers, Sherlock gasps and rocks against him. John can feel himself going wet to the fucking _wrist_. He wonders at the marvels of nonhuman biology.

Sherlock tips his head back and pants. "I'm ready," he says. "Do it."

"Fucking hell."

Sherlock shifts his weight forward, giving John the maneuvering room to steady and aim. At the first careful nudge of John's cock, he pushes back, relishing the stretch and slide of first penetration. He lets out his breath in a long, resonant "oh."

John's breath, meanwhile, is shallow and shaky. The odd, nervous feeling hasn't dissipated like he thought it would. It's intensifying, in fact, and he almost starts to worry. But he can worry about himself later. He's got Sherlock to worry about for now.

John rubs his hands up and down Sherlock's thighs. "Better?"

Sherlock just whines, leans down, nuzzles into the crook of John's shoulder, and presses his lips to John's neck. He doesn't bite yet. His lips are wet and parted, though, and behind them, John knows, is the silent threat of sharp teeth and insatiable thirst. John shivers.

"I promise, it doesn't hurt long," Sherlock murmurs, "and then it feels beautiful. I'll only take a little. Please, John. I…I _want."_

For a moment, John wonders if Sherlock can control minds. He's certainly doing a number on John's.

John grits his teeth and leans his head to the side, which bares his neck to Sherlock's mouth. That mouth breaks open against him with a low moan. Sherlock's fangs rake dry over his skin just once before setting in place and—

_—biting down._

John gasps. They're either very sharp or Sherlock is just that strong. It took no effort at all for them to pierce through skin.

He grimaces for a minute. It hurts more than it did before, though the pain isn't unbearable. No worse than a blood draw really, and he minds this much less.

But then Sherlock sucks, and a very different feeling washes over John. He gasps again, but not in pain or surprise. His vision is lighting up like sparkling fireworks in the night sky and his face has come over all hot and his spine feels like a live wire. This feels nothing like what happened before. That was standing in the ocean and the gentle push of the tide. This…this is free fall.

Feeling as if he's being operated by remote control, John draws his feet up under himself and pushes up. Sherlock, impaled as he is, breaks his drinking to groan against John's neck, then returns to his suckling. John takes this as encouragement and doesn't stop. He rolls his hips in time with Sherlock's drinking, long pulls punctuated by short drops. Sherlock pushes to meet him as John tries to keep breathing through the miasma of sex and hunger that's heavy in the room.

Slowly, John becomes aware that something is changing. He blinks. Something dawns.

"You're getting warmer," he says.

John can see the well-fed flush spreading down Sherlock's body, warming him until he feels hotter than even a human should. John wonders how far it would go if he let it. He wonders if he could go so far as to bring Sherlock back to life. It feels unspeakably good, the very height of altruism, this literal gift of life to his friend. Suddenly, he knows how far he'd let it go, and he has to comb his fingers into Sherlock's hair and clutch him very close.

"Oh God, I'd let you," John sobs. "I'd let you bleed me dry if it would save you."

Sherlock makes a desperate sound and pulls away from John's neck. He clenches around him and jerks upright, back arching into a perfect curve. A single red drop streaks from his lip and down his chin and neck. He rocks back and forth on John's cock, gasps, clutches clumsily at John's shoulders, and comes.

Sherlock seems to come for a very long time. His cheeks are—God, they're—flushed pink, actually, properly flushed, all the way down his neck and chest. When he bites his lip, it comes away red and swollen. His fangs have receded, and with his eyes shut, he looks beautifully, entirely alive.

John closes his eyes and sighs as Sherlock comes down, shaking, and catches him in a kiss. Sherlock is less urgent now. John is even less. Strange, considering he's still hard as stone and balls-deep in a truly fit man. But he's at peace for the moment. He feels…safe. Or at least right,like this is where he is supposed to be. John hums and continues kissing Sherlock. Is this the first time they've kissed? It doesn't feel like it.

Sherlock pulls back. John chases him for a second, but Sherlock bares his teeth. John takes the hint and falls back onto the pillow. It turns out to just be not a threat, but a smile, a wide, "case, John!" grin.

"Well, John," he says, in a resonant, come-fuck-me voice that makes the hairs on the back of John's neck stand on end, "what are we going to do about you?"

———

Everything is _wonderful_.

Sherlock is wonderful, and John is wonderful, and why in the world had Sherlock resisted this for so long?

Sherlock licks his lower lip. John's blood doesn't taste anything like red wine. Color is not taste, after all. It's...richer, somewhere halfway between dark chocolate and filet mignon. No, that's not it at all. The crux of the problem is that there are no words in any language Sherlock knows to describe the taste. He can only describe how it feels—how _he_ feels—satiated, indulged, intoxicated, _complete_.

The demand roiling in Sherlock's gut has abated for the time being, giving way to a lazy, warm, sated glow. He sways languidly back and forth on John's prick.

Meanwhile, John is getting restless. He squeezes Sherlock's hips. "Yeah. Do that again?"

A request, not an order. A different feeling seeps into Sherlock's chest. He tamps it down, shifts his weight, and starts coming down harder on John's cock. "Better?"

John just twists, moans, and scratches his fingernails encouragingly over Sherlock's skin.

"You're wonderful," Sherlock murmurs. He reaches up and touches his fingers to just below the small puncture wounds in John's neck. "God, what did I do to deserve you?"

There's a desperate, scrambling sort of feeling in Sherlock's chest at those words. But more important than that is the way John is now biting his lip and clutching at Sherlock's waist.

"Sherlock," he says, "I'm—I'm gonna—"

Sherlock purrs, low and resonant, and it seems to unwind something in John. John clings to Sherlock's hips and bucks up as he comes. Sherlock sighs.

"Yes," he says, smoothing his hands up and down John's sides. "Just like that. Good. So good."

After a while, John relaxes. He slides out—both of them wince—and curls up against Sherlock's side. Sherlock nuzzles into the crook of his neck and licks at the bite.

"Mmm," John hims. "That shouldn't feel that good."

It feels fantastic to Sherlock. Perfect, in fact. He may say as much, but he's not sure. It's hard to be entirely sure of anything at this juncture.

Some time later, John says, "That was...something."

He is grinning. It's rather a stupid grin, but that's just John. Sherlock smiles back.

"What, er, was that?" John asks. "Not the biting bit. Obviously I know what that bit was. But the—smelly bit, and the leaky bum bit?"

Sherlock laughs. John's grin widens.

"Later," Sherlock drawls. He throws one leg over John's waist. "Sleep now."

He shuts his eyes. He feels like a well-fed cat napping in the sun must. He cannot remember ever having felt so perfect in his life. It is as if a master builder inspected him and filled up all the cracks, painted over everything that's chipped and peeling, and stabilized the foundations.

Sherlock is not just sated. He is whole.

———

That night, John does not dream of anything.

———

Sherlock feels better than he has in years. He isn't hungry in the least. His senses are heightened to the maximum and he can feel strength humming through his body.

He breathes in and smells _everything_. Mrs. Turner and Mrs. Hudson are enjoying herbal soothers in Mrs. Turner's sitting room next door. It rained for an hour this morning. The biryani in the fridge has gone bad, and it's affecting Sherlock's mold experiment.

Above all this, Sherlock smells _John_. He smells the sweet salt of dried perspiration on John's skin, and John's aftershave from four days ago, and the decaf coffee he drank—last thing he had, he hasn't eaten or drunk in—never mind; he can smell the lactic acid metabolizing in John's system, and the copper-and-red-meat smell of John's blood, and—

—of John's _blood_ —

Oh, God.

Sherlock opens his eyes.

It takes him a moment to realize it's nearly sunset. The light is so dazzling to his newly sensitive eyes that at first he thinks it's midday. He comes quickly to the relevant realization: John's hardly gotten up since this began…two days ago? Sherlock swallows down his revulsion.

John is laid out on his back with one hand curled by his face. His neck is caked with dried blood. There's another brown splotch of it on the pillow where John must have rubbed it open in his sleep. He looks so small, so soft, so pale. His pulse flutters in his throat. Sherlock aches to draw him close and lick him clean, to gently bite in and drink.

The thought is enticing. The thought is appalling.

It is not enough for Sherlock to merely sample John Watson. He will only devour. It's plain from the way he feels today, so bright and clear and high. Every cell in his body longs to keep this man and be kept by him, to recapture this feeling as often as he can. Sherlock will destroy him if he is allowed to continue, and that must not happen. He will not allow it.

Sherlock stands up and moves away like he is being washed down a drain. He would kiss John before he leaves, but he knows he will not stop if he does.

Before the sun has gone down, he is gone.

———

Blinking drowsily all the while, John begins to surface.

He still feels sort of…dazed. Drunk. The bite on his neck throbs. He dares to stretch his neck to the side. It's sore, but it's not unbearable. John had a short-lived piercing that felt much the same.

He rolls over and throws out an arm, only to find the other side of the bed empty. He reaches for the clock on the bedside table and frowns. Only just past sunset. Sherlock won't have been up for more than an hour.

With a grimace, John climbs out of bed. He pulls on his pyjamas, nicks Sherlock's dressing gown from where it's hanging on the door and staggers out into the hall.

The curtains are open, letting in the dim light of the London evening. The sofa is still in the same sorry, rumpled state it had been when John had gone upstairs to bed two days ago. The kitchen is in the same casual disarray. And the coatrack by the door is missing the dark tweed greatcoat that had hung there.

John's stomach turns over.

He could have just gone out. Errands, or something. Even as the thought occurs, John rejects it. He knows exactly what's happened. This—all this, all that happened—had been the line. Sherlock finally knew exactly how much human was too much. An ache blooms from John's temples throughout his skull. He winces and squeezes his head between his hands.

It's all so much. Too much. He can't even begin trying to think it all through right now, not this tired and sore and sick.

John turns back down the hall and climbs back into Sherlock's bed. If he could just sleep…

———

Sherlock isn't sure how he gets to Mycroft's.

There is a vague memory of slogging through the setting sun with his collar up, his head down, and a pulsing ache in his stomach. His earlier vigor has evaporated. Now, he can barely keep his legs under him.

He better remembers the moment he leans against Mycroft's door. When Mycroft opens it, Sherlock stumbles and nearly faints straight into his arms. He catches himself on the doorframe at the last second.

"If I could—trouble you," he says, with some difficulty.

Mycroft's face crumples inwards with misery. "Oh, Sherlock."

Sherlock's throat is dry. He swallows. "Send someone for John."

Mycroft's eyes widen. "You didn't—"

Sherlock shakes his head fervently. "Not yet." He is so very tired.

That is the moment that his legs go out from under him at last, and he collapses.

———

John sleeps.

He half-wakes at some point to take a piss and a couple paracetamol for his splitting headache, then goes straight back to bed. Some hours later, he's awoken again by his stomach cramping up. He bolts for the toilet and is just in time to retch into the bowl.

John rests his head on the seat for a minute. The cold feels good. Is he running a temperature? He should check. First, though: sleep.

He doesn't remember getting back to bed. The next time he wakes, it's because he's freezing. The sheets are sticking sweat-damp to his skin and his teeth are chattering and he can't stop shaking.

This is wrong.

He reaches out to snatch his mobile off the bedside table before retreating beneath the blankets. He punches in a text and hits "send."

Having done all he can, John curls into a tight ball and shakes.

———

Everything is foggy again for some time.

Someone takes Sherlock upstairs. Perhaps it is Mycroft, although they will both pretend it is beneath him when they are lucid. In any case, Sherlock comes to in Mycroft's downstairs guest bedroom.

"Ah," Mycroft says. He is sitting in the armchair in the corner, a laptop perched on one knee. He sets it aside. "I do hope—"

"Don't let me out," Sherlock demands. He is staring at the ceiling"Not if I beg. Don't let me leave."

He is going to beg. He can tell. He wants to already.

Mycroft grimaces. "You won't be reasoned with, then."

"Reason?" Sherlock laughs bitterly. "Certainly not, if the evidence of John's red blood count is to be believed."

Mycroft expression remains impassive, but he jerks back as if he's been slapped. "That isn't what I meant."

Sherlock turns over and slants an anguished look towards his brother. "I know what you meant."

"Then you know that I can't let this slide."

"There is nothing you can—"

"I am not the one you should be speaking with," Mycroft says gently.

Sherlock grimaces. His head is _throbbing_. "The influence of biological imperatives has compromised John's ability to consent. I cannot—"

"Is that fair? Categorically denying John's right to his bodily autonomy?"

_"I_ didn't deny him, it was—"

"Was it? Did he do anything he would not have agreed to when lucid?"

"It would not have been necessary—"

"That isn't an answer."

"If I had been able to impress upon him—"

"Who are you to make his decisions?"

"He was affected."

Mycroft laughs. "More so than he ever is when you're around?"

"You know it!"

"He wasn't out of his control."

"You can't know that." Sherlock curls into himself. "Now go away."

Mycroft sighs. "As I said: unreasonable."

"Go away!"

Mycroft goes.

———

"He's not been up in three days, ever since—well. You'll see."

John turns over. Mrs. Hudson is talking to someone. It's probably about him.

"I'll go and see how he's doing. I got a funny text from him an hour or so ago."

Even through the fever, he recognizes Greg's endearing, husky voice. Had he texted Greg? He must have.

John musters up his strength and sits up. This plan works swimmingly for a moment. Then his head goes all weightless, the blood rushes from his face, and he has to quickly lie back down. This is how Greg Lestrade finds him a minute later.

John cracks an eye open. "Ta. Greg. If you'll just give me a—ohh, no." He tries to sit up again, to the same results.

"Christ, no, lie back down, you're a sight," says Greg. "I'm getting you a paracetamol."

John shakes his head. "Doesn't do much."

"Well, I'll get you one anyways with a glass of water and we'll see how it goes."

John nods. While Greg is off fetching supplies, he manages to get his head up a little.

Greg returns with a tray of biscuits, water, and two paracetamol. John takes a biscuit first. Best not take anything on an empty stomach. Greg sits on the bed beside him.

"You sure you don't need to go to hospital? Only, your landlady said you'd not been up in a while."

John shakes his head. "Nah. No need. Pretty sure I know what I've got, and there's no doctor in the world can cure it, so..."

He regrets the words immediately. Instead of wincing, he takes another bite of the biscuit.

Greg frowns. It's a familiar thinking-frown, the sort he puts on while Sherlock is talking. John makes himself busy with the water and paracetamol and biscuit.

The moment Greg puts it all together is obvious. "Oh, Jesus. Did you two..."

Just thinking about it makes John's chest tighten and his stomach clench threateningly. He shuts his eyes. "Yeah."

"Huh." Greg looks John up and down with something halfway between pity and fear. "God. And he—he did this to you?"

John frowns, then shakes his head. "Um. No. At least, if he did, it wasn't on purpose."

He thinks back to those two days and tries not to be swept under by the powerful wave of yearning that crashes over him. It had all been very...primal. Almost animalistic. John can remember feeling almost as if his body was not his own. Sherlock's certainly hadn't seemed to have been. Slowly, he figures out how to put it to words.

"It was like...nature hatched a plot to push us together," he says. "Sounds barmy, I know. But it was like we couldn't not...you know."

Greg's cheeks color. "Um, yeah." He clears his throat. "Are you saying...you didn't want...?"

John grimaces. That's the thing, isn't it? Because he _did_ want. But he'd always assumed Sherlock was above that, and that if John gave in, the temptation to let Sherlock go too far would be too strong. John is so very, very addicted to that rush of danger. The closer he gets to the edge, the stronger the high. He could trust Sherlock, who was, above all else, in control. But could he trust himself?

"Sometimes we want more than we should have," he says.

Greg sighs. "Oh, God, I was afraid of this."

John's brow furrows. "Sorry?"

"This...self-flagellating bollocks."

"This— _what?"_

"I've seen Sherlock do it a hundred times. Thinks it's very secret when he does it, but anyone with eyes can see him look at you and then—anyways. Look, my point is, if you two'd trust yourselves the way you trust each other, you'd be a right sight happier."

John opens his mouth to respond and finds he has no reply. He takes another bite of his biscuit instead. Greg lets the silence run. John chews the biscuit, swallows, tosses back the paracetamol and chases them with water.

———

Greg leaves after a half hour or so. The next time John wakes up, the flat is empty. He musters his strength and manages to stagger all the way to the kitchen and make himself some toast. Tea he deems too arduous a task to contemplate just yet. Meagre breakfast in hand, he sinks into his chair.

"Ah, glad to see you up and about."

John startles so hard he crushes his toast into squished-up bread and crumbs. Mycroft, in his oh-so-Holmesian way, has appeared in the parlor without making any kind of sound.

John throws his ruined toast aside and brushes off his shirt. "Oh, for _fuck's_ sake," he snaps. "What am I, some kind of—vampire-stricken Scrooge? Are you the Ghost of Vampires Past, Present, or Future?"

Mycroft lets the comment slide with no more than a raised eyebrow. "If I could have a moment of your time…?"

John raises an eyebrow right back, telegraphing "as if I have a choice." Mycroft cedes the point and takes a seat in Sherlock's chair.

"I imagine you need an explanation," Mycroft says.

John snorts.

"That is…fair." Mycroft sighs, then readjusts himself to settle more comfortably into Sherlock's chair. John is struck by an irrational urge to throw him straight out.

"Customarily, Sherlock would be expected to provide one. Under the circumstances, you will have to settle for myself as a substitute."

John nods, a little "carry on" gesture.

"You must try to understand, this is a difficult concept to explain. It is generally revealed piece by piece over a much more extended learning period, simply because it's so much to take in. This biochemistry and the customs around it are integral to our society and culture."

John grimaces. "Which—of course—Sherlock has opted out of."

Mycroft dips his head. "Exactly. The problem with his decision is that choosing not to participate in the cultural aspects does not exempt him from the biochemical impulses that led to those cultural traditions in the first place."

John frowns and rubs a hand across his brow. "Alright, I…think I'm following. Maybe. Just—pretend I'm not. Explain it to me like you'd explain to…whoever usually hears this speech."

"Very well." Mycroft cross his legs at the knee. "You are familiar with the particular predator adaptation of mimicry?"

"Yeah. Like—those fish with the lights on top to lure other fish."

"Just so. Or the more famous Dionaea muscipula, or Venus fly trap. The most similar analogy is with a particular species of katydid, which mimics the mating song of its prey. The unsuspecting insect is attracted to what it thinks is a willing partner. Instead, it becomes the katydid's meal."

With a sinking feeling, John sees just where this is going.

"Our kind exhibits a similar trait. Upon prolonged exposure to a suitable human, a series of biological and chemical changes are set in motion. Eventually, the hormone levels in both partners peak and result in an…event. Usually a feeding triggers the cycle. It sometimes happens the other way around, particularly when two partners have denied the natural biological urges for some time."

John swallows. He feels vaguely ill. Is that nausea he's feeling? Or is it…?

"So," he says, "I was just a…suitable lunch." Yeah, he is most definitely feeling ill now.

Mycroft shakes his head vehemently. "Not at all. That might be how it worked with some partners, but this is a…special circumstance."

John folds his arms over his chest. "Go on."

Mycroft pinches the bridge of his nose. "This is the precise reason this conversation is to last weeks or months and happen between partners. But…needs must." He sighs. "Not just anyone is 'suitable.' In a hundred years, I have met two such suitable people. Would you care to hazard how many Sherlock has met?"

A muscle in John's jaw flexes.

"No one has yet found what it is that makes two partners compatible. There is little warning before the dreams and urges begin, the signs of the body trying to force their hand. On a biological level, the relationship is symbiotic. The vampire is meant to protect the human with his superior physical strength, as the human provides both nourishment and, eventually, reproduction."

John pales. "Reproduction?"

Mycroft waves a dismissive hand. "The idea is that the human partner will be eventually turned."

John breathes a sigh of relief.

"We have a word for these sorts of mates that defies translation," Mycroft continues. "Portions of the concept have bled into some human traditions. The Chinese 'red string of destiny,' for instance, and the concept of soulmates. Both of these come short of capturing what such a person is in our culture. A vampire and human who are linked by these processes are, to each other, almost literally everything. Once the cycle passes, they are joined by an unbreakable bond. Prolonged separation will result in accumulative, accelerative decline, something you are already feeling. I assure you, whatever you are suffering, Sherlock is experiencing twice over. He is, after all, the one who walked away." Mycroft grimaces at that. "To walk away from one's mate is…unthinkable to us. Under usual circumstances, it would be considered an act of unforgivable cruelty. But these are not usual circumstances."

John's mouth is dry. Perhaps he should have attempted the tea after all. He unsticks his tongue from the roof of his mouth.

"So," he says, " you're telling me that Sherlock and I are…mated. Forever." Speaking it out loud hurts something, but…not in an entirely bad way. Like icing a sore limb.

"More or less."

John's vision flickers. He's baffled for a moment, until he realizes he's forgotten to breathe. He inhales. It doesn't help much.

Mycroft steeples his fingers in front of himself. The posture is so very Sherlock that it makes John's chest hurt. "Sherlock held all this back from you for reasons I am sure you can extrapolate. To be short, it was the usual: a misguided desire to protect you, the ridiculous notion that he knows best, and so on. He ran in hopes that it might sever your connection and save you from him. I know—I know, Dr. Watson, believe me, I am aware of how insane and self-absorbed my brother is."

"You're bloody well right!" John finds himself on his feet, and isn't quite sure how he got there. "That absolute fucking—wanker!"

The corner of Mycroft's mouth is tightening in an unreadable expression.

"You!" John jabs his finger in Mycroft's direction. "You know how to fix this…bollocks."

Mycroft shrugs. "Naturally. It's quite simple. The choice my brother tried to make for you is this: do you accept your irrevocable connection, or resent it? Or, do you live the half-life you are suffering now?"

John stops.

He thinks.

He thinks of Sherlock's face as he looms over a very, very bad man. He thinks of the pang of pain when Sherlock's teeth pierce his skin. He thinks of Sherlock's face as he comes, and the perfect O of his mouth. He thinks of making a kill shot through two windows, and jumping in front of a laser sight, and all of a sudden he thinks that there was never really a choice after all.

John strides over to the door, wrenches it open, and pounds down the stairs. There is a car waiting outside. He gets in. The driver pulls it away from the curb without a word.

Minute by minute, the ache in John's head and the churning in his stomach ease. It all feels so…correct. God, it's ludicrous how right it feels. John should be worried, alarmed even, by how destined it seems.

Instead, he looks out the window and smiles.

John doesn't need to be told when they're at the right place. He just about trips over his own foot getting out, runs up the steps, and pounds on the door.

"Sherlock?" He swallows around a large lump in his throat. "Come here, you bastard. We're having a talk." He rings the bell a few times for good measure. "At least, I'm going to do a lot of talking at you, and you're going to listen. Come on, you—"

The door flies open. Suddenly, there Sherlock is.

He stands there for a moment, blinking in the last rays of sunset, taking in the scene. John's anger evaporates.

"I…" he says hesitantly. "I talked to your brother."

Sherlock is still just staring.

There are hundreds of things John could say right now. He starts with the most important.

"Come back," he says.

Sherlock opens his mouth. Before he can say anything that'll ruin it all, John takes him by the shoulders, tugs him down, and kisses him soundly.

John remembers that there were going to be words. He had some kind of a speech about his free will and how he would've chosen this of his own volition if anyone had bothered to ask him. There was also quite a lot about Sherlock in it, and about how John feels for him, and how John would rather have bled out in the desert than give him up. There was also a good deal of angry bits along the lines of "how dare you make my decisions for me" and "fuck you for thinking you know what's best for us." But kissing seems like a better way to say most of that anyway. It's more John's style too, the kissing.

"I couldn't focus," Sherlock gasps. "God, I could hardly _breathe_."

John laughs with absolute delight. "I thought breathing was boring."

"No, breathing is marvelous," Sherlock insists, and proves the point by pressing his face to John's neck and breathing in deeply enough that John feels a chill.

"Oh," he says. "Oh, Sherlock."

Sherlock presses his mouth to John's neck, just his lips, just feeling, and John's knees go weak.

"Inside," he says. "Now."

Sherlock is stumbling backwards and dragging John with him. They leave the door hanging open, too busy with each other to pay it any mind.

"Where can we—" John gasps, as Sherlock's mouth breaks open over his neck and teeth drag wetly over his skin.

"Anywhere," Sherlock growls.

They sink to the floor together. Sherlock is laving his tongue over the wounds from his earlier bites, flat front teeth tugging at the sore edges. John makes a helpless noise.

"God. God, _please_ , Sherlock."

John doesn't even feel the preliminary scrape as Sherlock sets his fangs in, only the moment they puncture flesh. He shouts out an uncontainable exultation.

Finally, finally, finally. He was always helpless to this. He was always going to end up needing this man this way.

Sherlock doesn't drink long, only enough to ease the icy coldness in his fingers and bring himself round to something around lukewarm. When he disengages, it is slow and heartrendingly careful.

"You're so good to me," he murmurs. "Why?"

John grins and shrugs. "Dunno," he says. "I love you, I suppose."

Sherlock grins back. The tips of his fangs are red with blood. The sight makes something flare in John—not desire, but something deeper. Stronger. More. With affectionate despair, he accepts that he never, ever wants to be rid of this man.

Sherlock flushes deeply. Blushes, he _blushes_ , and it is all because of John that he can, and what a gift it is.

"I…good," Sherlock stammers. "I—also."

"I should also mention what an absolute bastard you are," John says, "for not explaining _any_ of this, and for _leaving,_ and for being the single most incredible man I have ever met in my life, and never in my life could I imagine being this fucking ecstatic over being stuck with such a massive tosser for the rest of my life."

Sherlock attempts to school his expression into haughty disdain. He fails completely. It just doesn't have the same sort of impact when he's just glowing like this, and John tells him as such. Of course, for him, it comes out closer to "quit trying to look frightening, you great idiot."

Sherlock responds by bodily picking him up, carrying him inside, and laying him out on a sofa. John is too gobsmacked by this development to put up any kind of resistance. Once his mate is well and truly spread out for him, Sherlock falls on top of John and kisses him.

"Well," he says, when they have kissed a fair amount. "I'll just have to keep trying."

"Do," John says, and pulls him back down.

 


End file.
